Resistive touchscreens and touchscreen overlays are used to provide touch-sensitive computer displays. Conventional resistive touchscreens and touchscreen overlays are composed of two flexible sheets coated with a resistive material such as indium tin oxide (ITO) and separated by an air gap or microdots. Conventional resistive touchscreens typically have high resolution (e.g., 4096×4096 DPI or higher), providing accurate touch control. There are two different types of resistive touchscreens, analogue and matrix (or digital).
The analogue type of resistive touchscreens consists of transparent electrodes without any patterning facing each other. During operation of a four-wire analogue touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur within a few milliseconds, registering the exact touch location as contact is made.
The matrix (or digital) type of resistive touchscreen has two substrates such as glass or plastic facing each other. Each substrate is coated with a resistive material such as indium tin oxide (ITO). The ITO coating on each substrate is patterned as striped electrodes. The striped electrodes are patterned as horizontal and vertical lines that, when pushed together, register the precise location of the touch.
Resistive touchscreens and overlays are commonly used in portable devices such as cellular telephones, tablets, etc. because they are inexpensive and generally available. Portable devices generally include support for wireless communication. Wireless communication generally is provided using radio frequency (RF) links. Radio frequency (RF) communication support requires some sort of antenna (or radiating structure) be included in the portable devices, which increases the number of components and the cost.
It would be desirable to implement a transitory touchscreen antenna structure.